Preparation of bis-dialkylamino phosphonous anhydrides



Patented Mar. 2, 1954 PREPARATION OF BIS-DIALKYLAMINO PHOSPHONOUS ANHYDRIDES Gilbert Spencer Hartley, Fulbourn, and Denis William Pound, Cambridge, England, assignors to Pest Control Limited, Cambridgeshire, England, a British company No Drawing. Application November 16, 1949,

Serial No. 127,792

8 Claims. (Cl. 260-545) This invention relates to the manufacture of compounds containing phosphorus having insecticidal properties.

It is an object of the present invention to provide an improved process for the manufacture of insecticidal compounds containing phosphorus and in particular bisdialky1amino phosphonous anhydrides.

It is a further object of the invention to use alkylamine is reacted with a solution of phos-- phorus oxychloride in an inert solvent in the presence of a tertiary amine which is of basic strength at least equal to that of pyridine and which does not undergo irreversible reaction with phosphorus oxychloride, and the product obtained is reacted with water and a tertiary amine which is of basic strength at least equal to that ofpyridine.

The use of a tertiary amine which is of basic strength at least equal to that of pyridine and which does not undergo irreversible reaction with phosphorus oxychloride in the first stage of the reaction facilitates the process and produces an improved product. Tertiary amine may be added in this stage in sufi'icient quantity to enable the second stage of the reaction to occur without further addition of tertiary amine, in which case the second stage of the reaction requires the addition of water only. Alternatively, the tertiary amine which is of basic strength at least equalto that of pyridine necessary in the second stage may be added at that stage, prior to the addition of water. It is desirable that the hydrochloride of the tertiary amine should remain in solution at least during the first stage of the reaction. This can be effected by choosing the tertiary amine, solvent and concentration accordingly. Additional pro= cedure is, therefore, necessary to recover the tertiary amine if it is desired on economic grounds to re-use it for another reaction.

reaction, improved yields Preferred examples of tertiary amines for use in the process are tertiary saturated alkylamines, e. g. methyl-dibutylamine, and N-dialkyl cycloalkylamines, e. g. N-diethylcyclohexylamine.

The preferred dialkylamine is dimethylamine.

A preferred embodiment of the invention will now be described with reference to the manufacture of bis-dimethylamino phosphonous anhydride. I

In the first stage of the reaction, anhydrous dimethylamine, or a solution of this substance in an inert solvent, is metered into a solution of phosphorus oxychloride in the solvent, the tertiary amine which is of basic strength at least equal to that of pyridine, being present in one or both of these solutions, the proportions being chosen to correspond with the equation:

1 2(CH3)2NH P0013 2NRz (CHahN o The tertiary amine NR3 may be used with advantage in excess of the amount required by this equation. The solvent is used in a sufiicient quantity to hold the tertiary amine hydrochloride in solution at the temperature of the reaction.

In the second stage of the reaction further tertiary amine On addition of further tertiary amine followed by water a reaction proceeds substantially in accordance with the equation:

( (CH3)2N %O It has been found that, as the tertiary amine in when pyridine is used the second stage of the result if water is used in slight excess of the stoichiometric amount corresponding with Equation 2. When a tertiary saturated alkylamine is used, however, we find this undesirable, the maximum yield being obtained with the stoichiometric amount. Tertiary amine is preferably present in excess.

To enable the tertiary amine to be recovered together with the solvent one of "several procedures may be adopted.

(a) Gaseous ammonia is next metered into the and/or solvent may be added.

5 6 References Cited in the file of this patent Number Country Date UNITED STATES PATENTS 631,549 Great Britain NOV. 4, 1949 Number Name Date OTHER REFERENCES 2,146,584 Lipkin Feb. 19 9 5 Ziele et a], Ber. deut. chem, vol 75, (1942), 2,487,859 Dickey et a1 Nov. 15, 1949 1127-33, 2,502,966 K D fi p 1950 Michaelis Liebigs Annalen, vol. 326, (1903),

FOREIGN PATENTS Number Country Date 10 23,752 Australia Jan. 5, 1949 

1. A PROCESS FOR THE MANUFACTURE OF A LOWER BIS-DIALKYLAMINO PHOSPHONOUS ANHYDRIDE WHICH COMPRISES REACTING ABOUT TWO MOLS OF AN ANHYDROUS LOWER DIALKYLAMINE WITH A SOLUTION OF ABOUT ONE MOL OF PHOSPHORUS OXYCHLORIDE IN AN INERT SOLVENT IN THE PRESENCE OF AT LEAST TWO MOLS OF A TERTIARY AMINE OF A STRENGTH AT LEAST EQUAL TO THAT OF PYRIDINE, AND REACTING THE PRODUCT FORMED WITHOUT SEPARATION THEREOF FROM THE REACTION MIXTURE WITH ABOUT ONE-HALF MOL OF WATER IN THE PRESENCE OF AN AMOUNT OF SAID TERTIARY AMINE EQUIVALENT TO AT LEAST ONE MOL THEREOF. 